JPH026239B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor laser device, and particularly to mode control thereof.

[Conventional technology]

2 shown in Fig. 3 as a conventional semiconductor laser device.
There was one with a cross-sectional structure of continuous stack type. In the figure, 1 is an active region (light emitting region), 2 is an n-
Upper cladding layer of AlGaAs, 3 is active layer of p-AlGaAs, 4 is lower cladding layer of p-AlGaAs, 5 is n
-GaAs block layer, 6 is p-GaAs substrate,
7 is a stripe formed by etching the block layer 5.

Next, the operation will be explained. When a voltage is applied to the laser chip, the current is blocked by the blocking layer 5 and therefore flows only through the striped portion 7. Therefore, only this portion of the active layer 3 becomes the active region 1, and the light generated in the active region 1 is confined in the vertical direction by the upper cladding layer 2 and the lower cladding layer 4 and oscillates.

[Problem that the invention seeks to solve]

However, in such a semiconductor laser device,
Since GaAs constituting the block layer 5 easily absorbs light, the odd-order mode 10 in which the electric field strength becomes 0 between the stripes 7 of the block layer 5 is the oscillation mode of the entire laser, as shown in FIG. It was easy to stand as a so-called super mode. the result,
In this case, the far-field pattern was bimodal, which caused problems such as difficulty in coupling with the fiber.

The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a semiconductor laser device that can make the transverse mode zero-order and have a single-peak far-field pattern.

[Means for solving problems]

In the semiconductor laser device according to the present invention, in the light absorption layer formed below the active layer having a plurality of striped light emitting regions, a region between the stripes of the light emitting regions has a thickness greater than a region outside the stripes. A thin region with low light absorption is provided.

[Effect]

In this invention, the thickness of the light absorbing layer between the stripes in the light emitting region of the active layer is made thinner than the area outside the stripes to reduce the gain loss between the stripes and the gain loss in the area outside the stripes. Since it is made high, the 0th order mode can be easily set up as a super mode.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a dual integrated semiconductor laser device according to an embodiment of the present invention. In Figure 1, the third
The same reference numerals as those in the figure indicate the same or equivalent parts, and 8 is a groove etched above the central part of the blocking layer 5a between the stripes 7 in order to reduce the loss between the stripes 7. Layer 5 has a thickness distribution.

Next, the effects will be explained. The process of oscillation in the active region 1 is the same as in the conventional case. However, in this embodiment, the block layer 5 between the stripes 7
Since the grooves are provided in the block layer 5a by etching a, the loss in this part can be sufficiently reduced.
In terms of utilization loss between the stripes 7, the zero-order and first-order modes can be made to stand to the same degree.
Furthermore, on the outside of the double stripe 7, the distance between the active layer 3 and the blocking layer 5 is still short, and light is absorbed, resulting in a large loss. Therefore, the primary mode, which has a large electric field strength in this part, has a large overall loss and is difficult to stand up. As a result, in this example device, only the 0th-order mode 9 shown by the dotted line in FIG. Laser light is obtained.

Further, in the above embodiment, the case where the current confinement mechanism is located below the active layer is shown, but the case where the current confinement mechanism is located above the active layer is shown in FIG. In the figure, the same reference numerals as in Figure 1 indicate the same or corresponding parts, and 15
is an n-GaAs substrate, 13 is an n-AlGaAs lower cladding layer provided under the active layer 3, and 14 is an n-GaAs absorption layer provided under the lower cladding layer 13. A groove 18 is provided between the double stripes 7. 12 is a p-AlGaAs upper cladding layer provided on the active layer 3, and 11 is a p-AlGaAs buried layer provided on the block layer 5.

In this device, since the light absorption rate is adjusted by providing a distribution in the thickness of the light absorption layer 14, the first mode can be cut off, and the same effect as in the above embodiment is achieved.

In the above two embodiments, the case of a double integrated semiconductor laser device has been described, but the present invention can be similarly applied to a case of three or more series, and the same effects as in the above embodiments can be expected.

Furthermore, as in the above embodiment, the present invention
In addition to semiconductor lasers based on GaAs,
InGaAsP, InP using InP instead of AlGaAs
The present invention can be similarly applied to semiconductor lasers.

〔Effect of the invention〕

As described above, according to the present invention, in a multiple integrated semiconductor laser device, the thickness of the light absorption layer between the stripes in the light emitting region of the active layer is made thinner than the area outside the stripes, so that the thickness of the light absorption layer between the stripes is reduced. A semiconductor laser device that outputs high-quality laser light with good coupling with the fiber, with low gain loss in the outer region of the stripe and high gain loss in the outer region of the stripe, so that only the 0th-order mode easily stands as a super mode. There is an effect that can be obtained.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a semiconductor laser device according to an embodiment of the present invention, FIG. 2 is a sectional view of a semiconductor laser device showing another embodiment of the invention, and FIG. 3 is a sectional view showing a conventional semiconductor laser device. The cross-sectional view, FIG. 4, is a diagram showing the zero-order mode and the first-order mode of the double semiconductor laser device. In the figure, 1 is an active region (light emitting region), 3 is a p-AlGaAs active layer (pn junction surface), and 5 is an n-GaAs
block layer (light absorption layer), 8 is an etched groove in the block layer, 10 is a first-order mode, and 14 is an n-
A GaAs absorption layer, 18 is a groove in the absorption layer. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Scope of Claims] 1. In a multiple integrated semiconductor laser device having a plurality of striped light emitting regions in an active layer formed on the same substrate, a light absorption layer formed below the active layer is . A semiconductor laser device, wherein between the stripes of the light emitting region, there is a region having a thinner thickness and a lower light absorption rate than the region outside the stripes. 2. The semiconductor laser device is a double integrated type, and in order to cut off the primary mode as the mode of the entire laser, the thickness of the region between the stripes in the light-emitting region of the light absorption layer is adjusted to the region outside the stripes. 2. The semiconductor laser device according to claim 1, wherein the semiconductor laser device is made thinner.